Within the past few years a new mode of communicating data has been accomplished by employing existing power lines. This mode of communications is referred to as broadband over power lines (BOPL). BOPL allows power utility companies to utilize their backbone electric grid infrastructure to offer customers high speed telecommunications services. Thus, power utility companies can now provide continuous high speed Internet access by modest changes of their existing plant.
Broadband over power line technology employs building, underground, and/or overhead power lines to conduct HF and VHF digital signals for allowing computers to connect to the Internet. The FCC views this technology as a competitive Internet access point, and the utilities view the technology as a means to use existing infrastructure to generate additional revenue from something other than power generation, transmission, and distribution.
One important concern about transmission of high frequency signals over power lines is electromagnetic radiation from the power lines into already used frequency channels. More specifically, for high frequency signals, the power line may act as an antenna that is able to emanate electromagnetic radiation leading to a significant interference to over-the-air radio services.
Under current FCC regulations, power transmission lines may emit signals having a power of up to 30 microvolts/meter at a distance of 30 meters from the source. However, such emission levels could easily interfere with other overlapping frequency channels, such as those used by the Amateur Radio Service. The problem with such interference is that it affects not only the Amateur Radio community, but also those who employ radio services using High Frequency (HF) spectrum.
Thus, there is a need for an arrangement that can effectively overcome the problems arising from transmission of high frequency signals over power lines.